you can make any of your aeons ultimate by customizing, my bahamut is kickass danger better than all my others, but for all aeons without no customizing, the win goes to the Magus Sisters, you have one as a means to defend loads of HP who basically just takes up the damage, you have a kickass fighter who uses a nice special that does over 9999 damage, and you have a caster who reflects it off the defender, not to mention her special which does spurts of small hits but like 100 times over. Magus sisters overdrive the delta attack as well. its basically having yourself a summoned party of strong aeons that can all exceed 9999 in DMG and HP, therefor replacing your party with limit to 9999 you can summon your aeon party (magus sisters) for the ultimat party. Magus sisters win probably against any other none customized aeon.

Just the point of being able to control 3 summons at the same time makes me feel bad for my enemies. Also, the Magus Sisters are very unique and add a "twist" to battles. Lastly, their overdrive is neat looking and powerful. Bahamut is powerful, and with it's humoungous build, he can take practically anything down in one hit. But, it's just like controlling any other summon. Unfortunatly, Bahamut (against a hard boss) gets one turn, then the boss, then Bahamut, then the boss, et cetera. On the other hand, the Magus Sisters would get 3 turns and then the boss, 3 turns, boss, 3 turns, boss, et cetera. To wrap this all up, if Bahamut dies in a battle, he can't come back. But, the Magus Sisters... if one of them die, you can persuade one of them to revive the one that died. So, you could carry out a long powerful battle with the Magus Sisters and a short powerful battle with Bahamut.

The Magus Sisters sometimes slack off. While any other aeon doesn't. Really not enjoyable. "Taking a break?" Thanks a lot Square. Even though their attacks are powerful, that shouldn't have been made and it really got annoying after my 2nd battle with them.